The Blood Brain Barrier (BBB) is essential for brain homeostasis and regulating the movement of compounds between blood and brain. Failure of the BBB leads to cerebral swelling, which is involved in many brain injury states including ischemic stroke. Angiopoietin-1 (Ang-1) has been shown to promote angiogenesis resistant to BBB leakage. Another novel transcription factor, Homebox D3 (HOXD3) promotes angiogenesis by inducing endothelial and smooth muscle cell proliferation and migration, stabilizing angiogenesis, and reducing ischemia/reperfusion induced BBB disruption. We will study BBB function from a novel perspective: BBB dysfunction after cerebral injury is part of the physiological repertoire of responses that result from stimulation of angiogenesis. As such, developing lines of therapy must consider angiogenesis in the larger scale BBB leakage resistance framework. We hypothesize that orchestrated administration of Ang-1 in the early stages of reperfusion and HOXD3 gene in the later stages of reperfusion promote functional angiogenesis in the injured mouse brain; including increased local CBF, reduced BBB leakage and edema, remodeled intact vessel walls, and improved neurological outcomes. We will first determine if Ang-1 increases junction protein expression (zonula occludens and claudin-1), and attenuates BBB leakage in the early stages (2 to 48 h) of reperfusion. We will then determine whether using an angiogenic factor, HOXD3, promotes functional angiogenesis during the late stages (3 to 28 d) of reperfusion. Further, we will explore the mechanism by which Ang-1 and HOXD3 induce angiogenesis with less BBB leakage. We propose a therapy-oriented research plan to manipulate angiogenesis after cerebral injury. Specifically, we seek to balance the prorepair and necessary induction of BBB plasticity for angiogenesis without the adverse effect of barrier integrity loss. With a novel mouse tMCAO model and TAT-protein delivery technique, we expect to develop specific therapies to attenuate BBB leakage associated with reperfusion, and to decrease ischemia/reperfusion brain damage by accelerating functional angiogenesis. [unreadable] [unreadable]